You can access this code snippet from your Project Manager index page. In the lower left corner there is a 'Make Project' button. This will copy the example into a new project so you can see all the .blend and code files.

Thank you for your answer.Yes I am. I did it but I need some more tutorial about it. I'm new in Blender and Blend4web so some part of codes is not clear to me.I have no idea about morph.blend file so I can not understand some parameters like "key_name" , slider structure ,… . where does it come from?

So here is a video about shape keys in Blender. It will show you where in the .blend file to start looking.https://youtu.be/Nlf959QT9VIIn the morph.blend file (if you copied the project) you may need to go to View > Toggle Maximize Area. And change some panels around to make it look like what you are used to.